Stoves and fireplaces for burning firewood, gas, coal, oil or the like are conventionally used as combustion apparatuses having a space heating effect. Such a combustion apparatus is equipped with a windowpane to allow visual check of the condition of flame from the outside. The windowpane needs to be transparent to visible light and have high thermal shock resistance. As materials having these properties, low-expansion transparent crystallized glasses are generally used.
The windowpane for combustion apparatuses is fixed to, for example, a metal frame of a combustion apparatus body through a gasket, an adhesive or the like. If the gasket or adhesive is visible from the outside, the design quality is impaired. Therefore, to hide a portion of the windowpane lying on the gasket or adhesive, a light-blocking layer is printed on at least part of the windowpane. For example, Patent Literatures 1 and 2 disclose methods for forming a layer containing an inorganic pigment powder and a glass powder on a surface of a transparent crystallized glass plate.